The present invention relates to a vehicle power steering system and more specifically to a hydraulic vehicle power steering system in which the resistance to actuation of a power steering control valve varies with changes in vehicle lateral acceleration.
A known power steering control valve has an inner valve member which is coaxial with and rotatable relative to an outer valve member or sleeve. To effect actuation of a power steering motor to turn steerable vehicle wheels, the inner valve member is rotated relative to the outer valve member against the influence of a torsion bar. Since actuation of the control valve is resisted by only the torsion bar, the resistance to actuation of the valve does not vary. Also, it is known to increase the resistance felt by an operator of a vehicle to actuation of a power steering system as vehicle speed increases.